Method and device for determining a gradient-limited cumulative setpoint torque from a setpoint torque of a closed-loop speed control

Abstract

In a method for determining a gradient-limited setpoint torque from a requested setpoint drive torque and a controller setpoint torque of a closed-loop speed control, the gradient of an unlimited cumulative setpoint torque, which is a function of the requested setpoint drive torque and the controller setpoint torque of the closed-loop speed control, is limited in a region of the zero crossing of the gradient-limited setpoint torque by a rate-of-change limitation to a maximally permitted or a minimally permitted value. The maximally permitted or the minimally permitted value of the rate-of-change limitation is a function of the controller setpoint torque of the closed-loop speed control.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a method and a device for forming a setpoint torque of a drive motor, in particular in connection with an operating mode of the drive motor having closed-loop speed control.[0003]2. Description of Related Art[0004]Rapid load changes or gear-change operations in motor vehicles can cause jerking, which is annoying to the driver and has a detrimental effect on the driving comfort. Known methods for reducing judder vibrations are based on avoiding an excitation of the drive train due to rapid load changes. In rapid variations, the setpoint drive torque requested by the driver via the drive pedal (or by driver-assistance systems) is therefore low-pass filtered with the aid of reference-forming elements, and / or its rate of change is restricted. This causes a delay in the torque generation and reduction.[0005]In addition, measures are taken in zero crossings of the drive torque, i.e., in the tr...

AI Technical Summary

Benefits of technology

[0011]It is an object of the present invention to provide a method and a device for torque formation in a drive motor, in which comfortable load changes are achievable with high dynamic performance while considering an intervention by the closed-loop speed control in an operation having rpm-regulated control close the to idling speed, with high control quality of the closed-loop speed control.

Problems solved by technology

Rapid load changes or gear-change operations in motor vehicles can cause jerking, which is annoying to the driver and has a detrimental effect on the driving comfort.

This causes a delay in the torque generation and reduction.

The interaction becomes problematic with an additional speed controller or idle controller which specifies a controller setpoint torque that is to prevent such things as, for example, chocking of a combustion engine used as drive motor.

However, an influencing of the controller setpoint torque by the following reference formation is not practicable from the viewpoint of the closed-loop speed control.

For one, the low-pass filtering delays controller setpoint torque, which causes a delay in a compensation torque induced by the closed-loop speed control, so that, for instance, choking of the combustion engine becomes more likely.

For another, the behavior of the controlled system varies considerably due to the non-linearity in the rate-of-change limitation, which requires a very robust controller and thus has a considerable adverse effect on the quality of the closed loop control.

Furthermore, there are problems in the transitions between rpm-regulated operation close to idling speed and torque-controlled operation above idling speed due to the fact that the gradient of the controller setpoint torque has an additional effect on the gradient of the cumulative setpoint torque.

This partially compensates for the rise in the limited setpoint torque, or it may even cause undershooting in the cumulative setpoint torque.

The acceleration no longer progresses optimally, and the achievable dynamic performance is limited.

The undershooter may cause the cumulative setpoint torque to cross zero multiple times, combined with poor behavior of the drive in a load change.

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